MR Inductively Coupled Active Septal Occluder for Cardiac Septal Defects

Stefan Michitsch, INSITE med. & Dept. of Physical Engineering University of Applied Sciences Gelsenkirchen, Biophan Europe, Castrop Rauxel GmbH, Germany

Lars Grosse-Wortmann, University Hospital RWTH Aachen, Germany

Klaas Tohnack, Biophan Europe, Castrop Rauxel GmbH, Germany

Bastian Urban, Andreas Melzer, Dept. of Physical Engineering University of Applied Sciences Gelsenkirchen, Biophan Europe, Castrop Rauxel GmbH, Germany

Background

Generally the percutaneous closer of an ASD (PFO, ASD II) is carried out under X-Ray with the known disadvantages of ionizing radiation, Iodinated Contrast agents and the lack of the soft issues contrast. The closure of the ASD is hampered by the artifacts of commercial Occluders that haven been tested. A new Occluder was developed, which works like a resonant circuit to increase the MRI signal.

Material & Methods

The Occluder consists of 2 connected coils (umbrellas) made of phosphorus bronze wire. The coils which represent the inductance and the connected commercial SMD (surface-mounted device) capacitor build a resonant circuit tuned to 64MHz, for 1.5T. Principle of the resonator is to reach a local signal enhancement by higher FA. The Occluder was fixed in an acryl measurement container and was positioned above a surface coil. The exam was performed in a 1,5T (Philips) with a FE-EPI imaging (TR/TE=19/7, EPI-Factor=3, FOV=235, FA=5-15°). Exams were carried out in long axis and 4-chamber view. Used solution was NaCl doped with 0,5 mmol/l Gd.

Results

By using of FA=5-15° local signal enhancements bigger than 400% were reached. The Occluder was successfully implanted and MR visualized in a fresh porcine heart.

Conclusion

The signal enhancement between both coils of the occluder is sufficiently homogenous. MRI guided implantation and the following diagnoses can be improved.

Keywords

Septal Occluder, MR Occluder, ASD Occluder